A cohort study on the development of bimanual force-control in highly aged individuals with and without mild cognitive impairments.

Rudisch, J.; Fröhlich, S.; Voelcker-Rehage, C.

Poster

Abstract

Bimanual coordination affords task-specific intra- and interhemispheric information processing in predominantly frontocentral brain networks. In role-differentiated bimanual tasks (RDBT) inhibition of crosstalk is necessary to avoid involuntary movements (e.g., when one hand manipulates and the other one stabilizes). Age-related cognitive decline might affect both, interhemispheric information exchange and inhibition of crosstalk, thus affecting RDBT performance. In this study, we investigated an RDBT in right-handed community-dwelling older adults (79 - 92 years) that are cognitively healthy (CHI: n = 76) or present mild cognitive impairments (MCI: n = 57). Participants performed a force-tracking task where they had to match a constant target force with their left (stabilizing role) and a sine-wave shaped force with their right hand (manipulating role). We were interested how the ability to produce a constant force was affected by age-related cognitive impairments. We therefore computed two measures of variability: 1. Coefficient of variation (COV) to investigate the magnitude; and 2. Detrended fluctuation analysis (DFA) to investigate the time-dependent structure of variability, with lower DFA scaling coefficients (DFA-α) indicating a more complex variability structure. Through the prospective cohort sequential study design, we followed up participants up to 3 times over 24 months. We used linear mixed effects modelling to investigate the effect of measurement time point, cognitive status, and sex on COV and DFA-α. For COV, we found only a significant effect for sex, with females showing higher COV as compared to males (t(130) = 2.67, p = .009, r = 0.23). Likewise, we found a significant effect of sex on DFA with females showing higher DFA-α than males (t(129) = 2.65, p = .009, r = 0.23). Additionally, we found a group x timepoint interaction with MCI showing a reduction of DFA-α over time whereas CHI did not. The effect did not reach significance level, however (t(151) = -1.40, p = .165, r = 0.11). In young adults, we have previously shown that an RDBT leads to a decreased complexity in the stabilizing hand as compared to a task where both hands maintained a constant force. This reduction of complexity is considered a signature of reduced neuromuscular degrees of freedom. Potential causes for an increased complexity in the MCI population during the RDBT, such as a focus on the force-maintenance role or a reduction of crosstalk, remain to be explored. Further research should include various other measures of complexity to confirm these results and use neuroimaging methods to investigate the relationship between active inhibition and complexity in this age group.

Details zur Publikation

Release year: 2023
Language in which the publication is written: English